23,766 research outputs found
Drastic improvement of surface structure and current-carrying ability in YBa2Cu3O7 films by introducing multilayered structure
Much smoother surfaces and significantly improved superconducting properties
of relatively thick YBa2Cu3O7 (YBCO) films have been achieved by introducing a
multilayered structure with alternating main YBCO and additional NdBCO layers.
The surface of thick (1 microm) multilayers has almost no holes compared to
YBCO films. Critical current density (Jc) have been drastically increased up to
a factor > 3 in 1 microm multilayered structures compared to YBCO films over
entire temperature and applied magnetic filed range. Moreover, Jc values
measured in thick multilayers are even larger than in much thinner YBCO films.
The Jc and surface improvement have been analysed and attributed to growth
conditions and corresponding structural peculiarities.Comment: Accepted to Appl. Phys. Lett. 88, June (2006), in press 4 pages, 3
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Nanonewton force generation and detection based on a sensitive torsion pendulum
In this paper, we introduce the experiment based on a sensitive torsion
pendulum for measuring and calibrating small forces at nanonewton scale. The
force standard for calibration is the universal gravitation between four masses
separated by known distances. It is realized by two test masses suspended as
the part of torsion pendulum and two source masses on a rotation table. Two
force generation mechanisms, optical force from radiation pressure and
electrostatic force by capacitive actuation unit, are designed and will be
calibrated by the gravitation force. We present our recent results of radiation
pressure measurements, and describe the design of capacitive displacement
sensing/actuating unit.Comment: This work has been presented on Conference on Precision
Electromagnetic Measurements, 8-13 June 2008, Broomfield, Colorad
Pareto Boundary of the Rate Region for Single-Stream MIMO Interference Channels: Linear Transceiver Design
We consider a multiple-input multiple-output (MIMO) interference channel
(IC), where a single data stream per user is transmitted and each receiver
treats interference as noise. The paper focuses on the open problem of
computing the outermost boundary (so-called Pareto boundary-PB) of the
achievable rate region under linear transceiver design. The Pareto boundary
consists of the strict PB and non-strict PB. For the two user case, we compute
the non-strict PB and the two ending points of the strict PB exactly. For the
strict PB, we formulate the problem to maximize one rate while the other rate
is fixed such that a strict PB point is reached. To solve this non-convex
optimization problem which results from the hard-coupled two transmit
beamformers, we propose an alternating optimization algorithm. Furthermore, we
extend the algorithm to the multi-user scenario and show convergence. Numerical
simulations illustrate that the proposed algorithm computes a sequence of
well-distributed operating points that serve as a reasonable and complete inner
bound of the strict PB compared with existing methods.Comment: 16 pages, 9 figures. Accepted for publication in IEEE Tans. Signal
Process. June. 201
Multiple Coloring of Cone Graphs
100學年度研究獎補助論文[[abstract]]A k-fold coloring of a graph assigns to each vertex a set of k colors, and color sets assigned to adjacent vertices are disjoint. The kth chromatic number Xk(G) of a graph G is the minimum total number of colors needed in a k-fold coloring of G. Given a graph G = (V, E) and an integer m ≥ 0, the m-cone of G, denoted by µm(G), has vertex set (V x {0,1,… , m}) U {u} in which u is adjacent to every vertex of V x {m}, and (x, i)(y, j) is an edge if xy ∈ E and i = j = 0 or xy ∈ E and |i - j| = 1. This paper studies the kth chromatic number of the cone graphs. An upper bound for Xk(µm(G) in terms of Xk(G), k, and m are given. In particular, it is proved that for any graph G, if m ≥ 2k, then Xk(µm(G)) ≤ Xk(G) + 1. We also find a surprising connection between the kth chromatic number of the cone graph of G and the circular chromatic number of G. It is proved that if Xk(G)/k > Xc((G) and Xk(G) is even, then for sufficiently large m, Xk(µm(G)) = Xk(G). In particular, if X(G) > Xc(G) and X(G) is even, then for sufficiently large m, X(µm(G)) = X(G).[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙
Some one-sided estimates for oscillatory singular integrals
The purpose of this paper is to establish some one-sided estimates for
oscillatory singular integrals. The boundedness of certain oscillatory singular
integral on weighted Hardy spaces is proved. It is here also
show that the theory of oscillatory singular integrals above
cannot be extended to the case of when and , a wider weight class than the classical Muckenhoupt class.
Furthermore, a criterion on the weighted -boundednesss of the
oscillatory singular integral is given.Comment: 24 pages, Nonlinear Anal. 201
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